UBUNTU: Ubuntu-4.10.0-37.41

[mirror_ubuntu-zesty-kernel.git] / mm / mremap.c

diff --git a/mm/mremap.c b/mm/mremap.c
index da22ad2a5678265ea9f2d0aa5ece9e14c519a494..30d7d2482eea1d04cf72b03bcd54d1d293f666e4 100644 (file)
--- a/mm/mremap.c
+++ b/mm/mremap.c
@@ -104,11 +104,13 @@ static pte_t move_soft_dirty_pte(pte_t pte)
 static void move_ptes(struct vm_area_struct *vma, pmd_t *old_pmd,
                unsigned long old_addr, unsigned long old_end,
                struct vm_area_struct *new_vma, pmd_t *new_pmd,
-               unsigned long new_addr, bool need_rmap_locks)
+               unsigned long new_addr, bool need_rmap_locks, bool *need_flush)
 {
        struct mm_struct *mm = vma->vm_mm;
        pte_t *old_pte, *new_pte, pte;
        spinlock_t *old_ptl, *new_ptl;
+       bool force_flush = false;
+       unsigned long len = old_end - old_addr;
 
        /*
         * When need_rmap_locks is true, we take the i_mmap_rwsem and anon_vma
@@ -146,7 +148,19 @@ static void move_ptes(struct vm_area_struct *vma, pmd_t *old_pmd,
                                   new_pte++, new_addr += PAGE_SIZE) {
                if (pte_none(*old_pte))
                        continue;
+
                pte = ptep_get_and_clear(mm, old_addr, old_pte);
+               /*
+                * If we are remapping a dirty PTE, make sure
+                * to flush TLB before we drop the PTL for the
+                * old PTE or we may race with page_mkclean().
+                *
+                * This check has to be done after we removed the
+                * old PTE from page tables or another thread may
+                * dirty it after the check and before the removal.
+                */
+               if (pte_present(pte) && pte_dirty(pte))
+                       force_flush = true;
                pte = move_pte(pte, new_vma->vm_page_prot, old_addr, new_addr);
                pte = move_soft_dirty_pte(pte);
                set_pte_at(mm, new_addr, new_pte, pte);
@@ -156,6 +170,10 @@ static void move_ptes(struct vm_area_struct *vma, pmd_t *old_pmd,
        if (new_ptl != old_ptl)
                spin_unlock(new_ptl);
        pte_unmap(new_pte - 1);
+       if (force_flush)
+               flush_tlb_range(vma, old_end - len, old_end);
+       else
+               *need_flush = true;
        pte_unmap_unlock(old_pte - 1, old_ptl);
        if (need_rmap_locks)
                drop_rmap_locks(vma);
@@ -201,13 +219,12 @@ unsigned long move_page_tables(struct vm_area_struct *vma,
                                if (need_rmap_locks)
                                        take_rmap_locks(vma);
                                moved = move_huge_pmd(vma, old_addr, new_addr,
-                                                   old_end, old_pmd, new_pmd);
+                                                   old_end, old_pmd, new_pmd,
+                                                   &need_flush);
                                if (need_rmap_locks)
                                        drop_rmap_locks(vma);
-                               if (moved) {
-                                       need_flush = true;
+                               if (moved)
                                        continue;
-                               }
                        }
                        split_huge_pmd(vma, old_pmd, old_addr);
                        if (pmd_trans_unstable(old_pmd))
@@ -220,11 +237,10 @@ unsigned long move_page_tables(struct vm_area_struct *vma,
                        extent = next - new_addr;
                if (extent > LATENCY_LIMIT)
                        extent = LATENCY_LIMIT;
-               move_ptes(vma, old_pmd, old_addr, old_addr + extent,
-                         new_vma, new_pmd, new_addr, need_rmap_locks);
-               need_flush = true;
+               move_ptes(vma, old_pmd, old_addr, old_addr + extent, new_vma,
+                         new_pmd, new_addr, need_rmap_locks, &need_flush);
        }
-       if (likely(need_flush))
+       if (need_flush)
                flush_tlb_range(vma, old_end-len, old_addr);
 
        mmu_notifier_invalidate_range_end(vma->vm_mm, mmun_start, mmun_end);